Endoscope system

ABSTRACT

An endoscope system includes a plurality of different endoscopes each of which has an illumination optical system for emitting light outward, an observation optical system for forming an optical image of a subject at the distal end of an insertion tube which can be inserted into the subject, and a solid-state imaging device for converting the optical image of the subject formed by the observation optical system into an electric signal, a plurality of different signal processors each of which drives a solid-state imaging device and processes the output signal sent from the solid-state imaging device to provide a video signal, and a plurality of different light sources each of which is compatible with one of the plurality of different endoscopes and supplies light to the illumination optical system. The system expendability is so excellent that the above equipment will be compatible with technologically-upgraded endoscopes, signal processors, or light sources.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an endoscope system permittingexpandable combinations of endoscopes, signal processors, and lightsources.

2. Description of the Related Art

Endoscopes have been adopted widely in recent years, so that anelongated insertion tube can be inserted into a body cavity to observeorgans in the cavity, or a treatment adapter can be routed through atreatment channel, if necessary, to perform various treatments.Endoscopes are used not only for medical but also industrial purposes;such as, observation or inspection of objects in pipes of boilers,machines, or chemical plants, or those in machines.

The aforesaid endoscope may be either an optical endoscope (so-calledfiberscopes) permitting observation with naked eyes based on image fibertechnologies, or an electronic endoscope having a solid-state imagingdevice at the tip of an insertion tube to observe subjects on a TVmonitor.

An endoscope apparatus having an electronic endoscope requires not onlya light source but also a signal processor for driving a solid-stateimaging device, and for processing the output signal of the solid-stateimaging device to generate a video signal. The endoscope apparatusprovides high-resolution images and permits easy image recording andreproduction.

Therefore, electronic endoscopes have taken over from fiberscopes as amainstream tool of endoscopy nowadays. The core of endoscopictechnologies has shifted from image fiber technologies to electronictechnologies. More specifically, a semiconducting technology relating toimprovement of a charge coupled device (hereafter, CCD) or any othersolid-state imaging device, an imaging circuit technology (video processtechnology) for driving the solid-state imaging device and convertingthe output signal into a video signal, and a light adjustment technologyrelating to a light source have become main targets that must be tackledin order to develop endoscope-related technologies.

Under these circumstances, an endoscope apparatus commercialized withstate-of-the-art technologies at one point in time rapidly becomes atechnologically obsolete because of rapid advancements in the fields ofsemiconducting, imaging circuitry, and light adjustment. Users who havepurchased certain products may be disappointed at finding the debut of anew product or an upgraded version.

Only certain types of signal processors and light sources can usually becombined with certain models of endoscopes due to the differences in thenumber of pixels of solid-state imaging device and the driving mode, orthe difference in color imaging; that is, field sequential orsimultaneous (color mosaic) imaging. Even if new products are put on themarket, they are nothing but improved versions of previous models. Inorder to utilize the improved part, users are required to purchase newendoscope apparatuses or keep using existing ones.

To cope with this problem, various proposals have been made to permitthe use of the same equipment regardless of the difference in the typeof solid-state imaging device or imaging mode. For example, U.S. Pat.Nos. 4,774,568, 4,816,909, 4,891,695, 4,926,258 all disclose endoscopesusing different types of solid-state imaging devices. U.S. Pat. Nos.4,853,773, 4,855,819, Japanese Patent Laid-Open No. 1988-200736,Japanese Patent Laid-Open No. 1988-220837, Japanese Patent Laid-Open No.1988-304221, and Japanese Patent Laid-Open No. 1990-305543 all discloserelated art capable of operating in different imaging modes.

U.S. Pat. No. 4,774,568 discloses an endoscope apparatus in whichendoscopes operating the same imaging mode but having different types ofsolid-state imaging devices can be used. Therein, a connector forconnecting between an endoscope and a main unit is provided with an IDdetection member for identifying the imaging position of a solid-stateimaging device incorporated in an endoscope, and the image format of areflected image or unreflected image. Depending on the signal the IDdetection member detects, it is determined whether the focal position ofa solid-state imaging device is set to forward observation, lateralobservation, or backward observation, or whether images are displayedlaterally or reversely. Thus, formed images are displayed at a correctposition on a TV monitor. In U.S. Pat. No. 4,816,909, an endoscopeconnector is provided with a ROM containing information indicating thenumber of pixels of a solid-state imaging device and the spectralcharacteristic for each endoscope. Then, depending on the informationread from the ROM, either a drive or processing circuit is selected.

In U.S. Pat. No. 4,891,695, at least one pixel element of a solid-stateimaging device in an endoscope is designed to that the area or at leastone lateral side will be the same as that of an effective pixel.Thereby, a pixel configuration is detected to control a video signalprocessing means. U.S. Pat. No. 4,926,258 discloses an endoscopeapparatus in which endoscopes having solid-state imaging devices providedifferent numbers of pixels. Therein, a drive signal containing ahorizontal transfer clock with certain frequencies is applied to asolid-state imaging device and then the signal read from the solid-stateimaging device is processed to generate a video signal.

On the other hand, U.S. Pat. No. 4,853,773 discloses an endoscope signalprocessing apparatus, supporting different imaging modes, wherein anendoscopic signal processing unit is equipped with a first signalprocessor for processing the signal sent from a field sequential typeimaging device, and a second signal processor for processing the signalsent from a simultaneous type imaging device. The endoscopic signalprocessing unit identifies the imaging mode of an endoscope connected,selects a corresponding signal processor, then outputs a video signal.U.S. Pat. No. 4,855,819 discloses an endoscope imaging system in which afield sequential type light source and signal processor, and asimultaneous type light source and signal processor are accommodated inone housing. Connectors are formed for both imaging modes, so thateither field sequential type or simultaneous type endoscopes can beused.

Japanese patent Laid-Open No. 1988-20736 discloses an endoscope imagingapparatus in which a common circuit is used as parts of a signalprocessor for field sequential type color imaging system endoscopes anda signal processor for color mosaic imaging system endoscopes. InJapanese Patent Laid-Open No. 1988-220837, a signal processor for fieldsequential type color imaging system endoscopes and a signal processorfor color mosaic imaging system endoscopes are mutually connectable, sothat one of the panels can be used to adjust the gain of the othersignal processor.

Moreover, Japanese Patent Laid-Open No. 1988-304221 discloses anendoscope apparatus in which an external TV camera of an endoscope whoseimage transmission optical system has a final image forming positionoutside of the main unit is provided with a type signal generationcircuit for generating an identification type signal. Depending on theidentification type signal sent from the type signal generation circuit,simultaneous or field sequential imaging is determined to select anassociated light source and signal processor. Japanese Patent Laid-OpenNo. 1990-305543 discloses an endoscope in which a user presses a switchto specify whether to adopt simultaneous or field sequential imaging,then a mosaic filter or a light transmission body is arranged by anelectrostatic motor on a photosensitive section of a solid-state imagingdevice depending on the simultaneous or field sequential imaging mode.Then, the identification signal sent from the type signal generationcircuit is checked to determine either the simultaneous or fieldsequential imaging mode, then an associated light source and signalprocessor are selected.

However, when a means for identifying the type of endoscope isinstalled, or light sources or signal processors of field sequential andsimultaneous imaging modes are prepared, the product becomes soexpensive that users have to incur an enormous amount of equipmentinvestment. Besides, the endoscope apparatus becomes very large andheavy.

Even if functions are installed in a single unit or system to cope withdifferent types of endoscopes, all of the functions are not used fornormal operation and many functions remain idle. This opposes theconcept of effective use of equipment and wastes equipment.

A unit or a function of a system a user is currently using anddissatisfied with differs from user to user. For example, a user may bedisappointed with insufficient resolution of endoscopic images, butanother user may be annoyed with slow light adjustment or coloraberration.

Even if a single unit or system is upgraded, partial improvements insemiconducting technologies relating to improvement of a solid-stateimaging device, imaging circuit technologies, or light source lightadjustment technologies are not implemented in the unit or systemaccording to needs from users.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an evolvable endoscopesystem in which an existing light source can be used in combination withnew endoscopes integrating advanced endoscopic technologies.

Another object of the invention is to provide an evolvable endoscopesystem in which an existing endoscope can be used in combination withnew light sources integrating an advanced light source technology.

Another object of the invention is to provide an evolvable endoscopesystem in which an existing endoscope can be used in combination withnew signal processors integrating an advanced signal processingtechnology.

Another object of the invention is to provide an evolvable endoscopesystem in which an existing light source can be used in combination withnew signal processors integrating an advanced signal processingtechnology.

Another object of the invention is to provide an endoscope systemallowing users to operate endoscope apparatuses integratingstate-of-the-art technologies with limited investment in equipment.

Another object of the invention is to provide an endoscope system forrealizing upgraded components with limited equipment investmentaccording to the needs of a user.

In order to achieve these and other objects, an endoscope systemaccording to the present invention includes a plurality of differentendoscopes, each of which has an illumination optical system foremitting light outward, an observation optical system for forming anoptical image of a subject at the distal end of an insertion tube thatcan be inserted into the subject, and a solid-state imaging device forconverting the optical image of the subject formed by the observationoptical system into an electric signal, a plurality of signal processorsfor driving the solid-state imaging device, and for processing theoutput signal of the solid-state imaging device to provide a videosignal, and a plurality of different light sources which are compatiblewith any of the plurality of different endoscopes and supply light toillumination optical system. One of the plurality of differentendoscopes is connected to a compatible one of the plurality ofdifferent signal processors and any one of the plurality of differentlight sources, thus forming an endoscope apparatus.

Other features and advantages of the present invention will be apparentin conjunction with the description below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 5 show the first embodiment of the present invention;

FIG. 1 is an explanatory diagram showing the connecting relationships inan endoscope system;

FIG. 2 is a specific configuration diagram of an endoscope apparatusincluding a first endoscope, a first video processor, and a first lightsource;

FIG. 3 is a specific configuration diagram of an endoscope apparatusincluding the first endoscope and first video processor, and a secondlight source;

FIG. 4 is a specific configuration diagram of an endoscope apparatusincluding the second endoscope, second video processor, and first lightsource;

FIG. 5 is a specific configuration diagram of an endoscope apparatusincluding the second endoscope, second video processor, and second lightsource;

FIG. 6 is a schematic diagram showing the second embodiment of thepresent invention and the connecting relationships in the endoscopesystem;

FIGS. 7 to 9 show the third embodiment of the present invention;

FIG. 7 is an explanatory diagram showing the connecting relationships inan endoscope system;

FIG. 8 is a specific configuration diagram of an endoscope apparatusincluding a first endoscope, a first video processor, and a first lightsource;

FIG. 9 is a specific configuration diagram of an endoscope apparatusincluding a second endoscope, a second video processor, and a secondlight source;

FIG. 10 is a schematic diagram showing the fourth embodiment of thepresent invention and the connecting relationships in an endoscopesystem;

FIGS. 11 and 12 show the fifth embodiment of the present invention;

FIG. 11 is a specific configuration diagram of an endoscope apparatusincluding a first endoscope, a first video processor, and a first lightsource; and

FIG. 12 is a specific configuration diagram of an endoscope apparatusincluding a second endoscope, a second video processor, and a secondlight source.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 5 show the first embodiment of the present invention.

As shown in FIG. 1, an endoscope system of this embodiment includes afirst endoscope 10 equipped with a CCD 18 as a solid-state imagingdevice, a first video processor 20 or a signal processor for driving theCCD 18 in the first endoscope 10 and processing signals sent from theCCD 18, a first light source 30 for supplying illumination light, asecond endoscope 40 equipped with a CCD 48, a second video processor 50or a signal processor for driving the CCD 48 in the second endoscope 40and processing signals sent from the CCD 48, and a second light source60 for supplying illumination light, as well as third, fourth, etc.endoscopes, third, fourth, etc. video processors, and third, fourth,etc. light sources, which are not shown.

In endoscope systems of this and subsequent embodiments, specificexamples will be described in conjunction with two endoscopes, two videoprocessors, and two or one light sources.

The first endoscope 10, first video processor 20, and first light source30 are technologically improved to produce the second endoscope 40,second video processor 50, and the second light source 60. In the lightof an endoscope apparatus including the first endoscope 10, first videoprocessor 20, and the first light source 30, an endoscope apparatusincluding the second endoscope 40, second video processor 50, and secondlight source 60 is provided as a next-generation endoscope apparatus.

In the endoscope system of this embodiment, the CCD 18 in the firstendoscope 10 is of a different type from the CCD 48 in the secondendoscope 40. This results in a difference in the number of pixels of aCCD or in the driving mode deriving from the differences in the numberof drive signals for driving a CCD, drive voltage, drive signal phase,and drive signal waveform. Therefore, the first endoscope 10 iscompatible only with the first video processor 20, and the secondendoscope 40, with the second video processor 50. Thus, the endoscopesand video processors are employed in pairs.

Strictly speaking, the drive condition for driving a certain type of CCDoptimally is not restricted to a specific value. The CCD can be drivenat, for example, 60 fields per second or 30 fields per second. Thisinvention provides compatibility between a CCD and a video processor(signal processor). That is to say, when a certain video processor candrive two types of CCDs optimally, these two types of CCDs are definedas of the same type. When only one of the two CCDs is driven optimally,the CCDs are defined as of different types.

If a user who owns the endoscope apparatus 1 shown in FIG. 2 includingthe first endoscope 10, first video processor 20, and first light source30 wants to improve the performance of some facility, the first andsecond light sources 30 and 60 may be used in combination to formendoscope apparatuses 2, 3, and 4 as shown in FIGS. 3 to 5 according tohis/her needs.

That is, this endoscope system allows users to upgrade part of thefunctions without purchasing a whole new endoscope apparatus. Inaddition, a higher-grade apparatus need not be installed to supportmultiple endoscopes. Thus, enormous equipment investment is not requiredand only minimum equipment investment is needed to implementstate-of-the-art technologies only in the facilities to be upgraded.

First, and endoscope apparatus i shown in FIG. 2 will be described. Theendoscope apparatus 1 is formed by connecting a first endoscope 10 to afirst light source 30, and the first light source 30 to a first videoprocessor 20 using a first connection cable 80 and a second connectioncable 81 which can be disconnected freely. Then, the first videoprocessor 20 is connected to a TV monitor 70 via a video signal cable 82that can be disconnected freely.

The first endoscope 10 comprises an elongated insertion tube 11 whichcan be inserted into a subject, a large-diameter operation unit 12coupled to the back of the insertion tube and a universal cord 13extending from the side of the operation unit 12. The first endoscope 10and the first light source 30 are connected using a connector 13ainstalled at the back of the universal cord 13, although the firstendoscope 10 and the first light source 30 can be disconnected freely.Thus, the first endoscope 10 and first light source 30 are coupledoptically.

A rigid distal end 14 is formed at the tip of the insertion tube Thedistal end 14 is provided with an illumination optical system 15 made upof an illumination lens for emitting illumination light outward and anobservation optical system 16 made up of an objective lens for formingan optical image of a subject.

The illumination optical system 15 is facing the emission end of a lightguide 17 formed with a fiber bundle. The light guide 17 runs through theinsertion tube 11, operation unit 12, and universal cord 13. Theincident end of the light guide 17 is arranged at the tip of theconnector 13a, so that illumination light originating from the firstlight source 30 can travel through the illumination optical system 15and illuminate a subject.

A CCD 18 for converting an optical image of a subject into an electricsignal is built in at the image formation position of the observationoptical system 16. Signal lines 19a and 19b for transmitting the driveand output signals of the CCD 18 run through the insertion tube 11,operation unit 12, and universal cord 13, then terminate on the side ofthe connector 13a.

On the other hand, the first video processor 20 comprises a CCD drivecircuit 21 for driving the CCD 18, a memory 22 for storing the outputsof the CCD 18 for three frames associated with R, G, and B fieldsequential light components, a video process circuit 23 for reading dataof one screen (three frames associated with R, G, and B field sequentiallight components) from the memory 22, converting the data into a videosignal, then displaying the video signal on the TV monitor 70, and alight adjustment circuit 24 for generating a light adjustment signal forillumination light according to the output signal sent from the videoprocess circuit 23, as well as a sample-and-hold circuit, a low-passfilter, and a matrix circuit, which are not shown.

The first light source 30 comprises an illumination lamp 31 for emittingwhite light, a luminance diaphragm 32 for controlling and varying thequantity of transmission light of the illumination lamp 31, a diaphragmdrive motor 33 for driving the luminance diaphragm 32, a convergingsystem 34 for converging light onto the incident end of the light guideof an endoscope connected, a rotary filter 34 which is located betweenthe converging optical system 34 and luminance diaphragm 32, andincludes R, G, and B color transmission filters arranged in thecircumference of a disk-like frame, a rotary filter drive motor 36 fordriving the rotary filter 35, and a timing signal generation circuit 37for generating timing signals.

The first video processor 20 is connected to the first endoscope 10 andlight source 30 via the first connection cable 80 extending from theside of the connector 13a of the universal cord 13, and to the firstlight source 30 via the second connection cable 81. Thus, the firstendoscope 10, first video processor 20, and first light source 30 arecoupled electrically.

The first connection cable 80 accommodates a signal line 80a fortransmitting the output signals of the CCD 18, a signal line 80b fortransmitting the drive signal sent from the CCD drive circuit 21, and asignal line 80c for transmitting the output signal of the lightadjustment circuit 24. The second connection cable 81 accommodates asignal line 81a for transmitting the output signal of the timinggeneration circuit 37.

Specifically, the first video processor 20 mutually controls the firstlight source 30. The first video processor 20 is compatible with eitherthe first or second light source 30 or 60. The first light source 30 orsecond light source 60 feeds a timing signal to each of the CCD drivecircuit 21, memory 22, video process circuit 23, and light adjustmentcircuit 24. The timing signals control the operation of the endoscopesystem.

In the endoscope apparatus 1, the timing signal sent from the timingsignal generation circuit 37 in the first light source 30 is fed to therotary filter drive motor 36, as well as the CCD drive circuit 21,memory 22, and video process circuit 23 in the first video processor 20.

Then, the rotary filter 35 is rotated by the rotary filter drive motor36 according to a specified timing. The CCD drive circuit 21 drives theCCD 18 in synchronization with the rotation of the rotary filter 35. Theoutput signal is placed in the memory 22. Data stored in the memory 22is read by the video process circuit 23 to generate an NTSC videosignal. The NTSC video signal enters the light adjustment circuit 24.

The light adjustment circuit 24 generates a light adjustment signal forcontrolling the diaphragm drive motor 33 according to the output signalof the video process circuit 23. The light adjustment signal passesthrough the signal line 80c in the first connection cable 80, then goesto the diaphragm drive motor 33. Thus, the aperture of the luminancediaphragm 32 is controlled.

Light emitted from the illumination lamp 31 is optimized in luminance bythe luminance diaphragm 32, transmitted to the rotary filter 35, thenseparated time-sequentially into light components having R, G, and Bwavelengths. Then, the light components are converged onto the incidentend of the light guide 17 by the converging optical system 34. Then,field sequential illumination light is routed by the light guide 17,then emitted over a wide angle from the illumination optical system 15.

As a result, an optical image of a subject illuminated is formed on theimaging plane of the CCD 18 by the observation optical system 16. Thephotoelectrically-transferred output of the CCD 18 is processed by thefirst video processor 20 to generate a video signal. Then, an optimalobservation image of the subject appears on the TV monitor 70.

In the foregoing first endoscope 10, the observation optical system 16has an observation depth of, for example, 8 to 10 mm, and the CCD 18 isa monochrome CCD providing 1000000 pixels and a sensitivity of 150 mV.The first video processor 20 provides an S/N ratio of 40 dB for thebrightness signal sent from the video process circuit 23. Theillumination lamp 31 in the first light source 30 is a halogen lamp, orpreferably, a xenon lamp providing a brightness of 4000000 Lux.

The timing signal generation circuit 37 in the first light source 30generates a timing signal for rotating the rotary filter 29 at 20rotations per second (20 frames per second) using the rotary filterdrive motor 36. According to the timing signal, the CCD drive circuit 21drives the CCD 18 at 60 frames per second.

When a user wants the endoscope apparatus 1 to provide higher lightadjustment speeds, the user should purchase only a second light source60. In this case, as shown in FIG. 3, the endoscope 10 is connected tothe second light source 60, and the second light source 60, to the firstvideo processor 20 via the first connection cable 80 and secondconnection cable 81. Then, the first video processor 20 is connected tothe TV monitor 70 via the video signal cable 82. Thus, an endoscopeapparatus 2 is formed.

The second light source 60, similarly to the first light source 30,comprises an illumination lamp 61 for emitting white light, a luminancediaphragm 62 for controlling and varying the quantity of transmissionlight from the illumination lamp 61, a diaphragm drive motor 63 fordriving the luminance diaphragm 62, a converging optical system 64 forconverging light on the incident end of a light guide of an endoscopeconnected, a rotary filter 65 which is installed between the convergingoptical system 64 and luminance diaphragm 62, and includes R, G, and Bcolor transmission filters arranged in the circumference of a disk-likeframe, a rotary filter drive motor 66 for rotating the rotary filter 65,and a timing signal generation circuit 67 for generating timing signals.

The second light source 60 provides higher performance than the firstlight source 30. This is to say, the illumination lamp 61 or a halogenlamp provides, for example, 6000000 Lux. The mass of the variable deviceof the luminance diaphragm 32 is reduced, and the power of the diaphragmdrive motor 63 is increased. The timing signal generation circuit 37generates timing signals at, for example, 30 frames per second (30rotations per second), and the first video processor 20 drives the CCD18 at 90 frames per second and outputs an NTSC video signal.

Therefore, a user who owns the first light source 30 can increase theluminance of illumination light from 4000000 Lux to 6000000 Lux), speedup light adjustment (lightened mass of the variable device in theluminance diaphragm 32 and higher powered diaphragm drive motor 63), andreduce color aberration (from 20 frames/sec to 30 frames/sec) merely byinstalling the second light source 60. Thus, the user can improve thesystem performance.

When a user of the first endoscope apparatus 1 is not annoyed with coloraberration in endoscope images but wants to improve image resolution,the user has to install only the second endoscope 40 equipped with a CCD48 providing more pixels than that in the first endoscope 10 and thesecond video processor 50 having an advanced imaging circuit technology.The first light source 30 can be used as it is.

Specifically, as shown in FIG. 4, the second endoscope 40 is connectedto the first light source 30, then the first light source 30, to thesecond video processor 50 via the first connection cable 80 and secondconnection cable 81. Then, the second processor 50 is connected to theTV monitor 70 via the video signal cable 82. Thus, an endoscopeapparatus 3 is formed.

The second endoscope 40, similarly to the first endoscope 10, comprisesan elongated insertion tube 41 which can be inserted into a subject, alarge-diameter operation unit 42 coupled to the back of the insertiontube 41, and a universal cord 43 extending from the side of theoperation unit 42. The endoscope 40 can be freely disconnected from thefirst light source 30 by removing a connector 43a installed at the backof the universal cord 43.

A distal end 44 of the insertion tube 41 is provided with anillumination optical system 45 and an observation optical system 46. Theillumination optical system 45 is facing the emission end of a lightguide 47, and a CCD 48 is built in at the image forming position of theobservation optical system 46.

The light guide 47 runs through the insertion tube 41, operation unit42, and universal cord 43. The incident end of the light guide 47 isarranged at the tip of the connector 43a. The CCD 48 is connected to asignal line 49a for transmitting drive signals and a signal line 49b fortransmitting output signals. The signal lines 49a and 49b run throughthe insertion tube 41, operation unit 42, and universal cord 43, andterminate on the side of the connector 43a.

The CCD 48 benefits from advanced semiconducting technology, andprovides, for example, 200000 pixels and a sensitivity of 300 mV. Withthe upgraded sensitivity of the CCD 48, the f-number of an objectivelens in the observation optical system 46 can be reduced. Theobservation depth ranges, for example, from 3 to 100 mm.

The second video processor 50 is designed exclusively for the CCD 48which has a different number of pixels from the CCD 18 in the firstendoscope 10. The second video processor has a configuration similar tothat of the first video processor 20. Even when either the first lightsource 30 or second light source 60 is used in combination, the secondvideo processor 50 drives the CCD 48 according to the timing signal,then processes the signal sent from the CCD 48 to generate a videosignal properly.

Specifically, the second video processor 50 comprises a CCD drivecircuit 51 for driving the CCD 48, a memory 52 for storing the outputsof the CCD 48 for three frames associated with R, G, and B fieldsequential light components, a video process circuit 53 for reading dataof one screen (three frames associated with R, G, and B field sequentiallight components) from the memory 52, converting the data into an NTSCvideo signal, then displaying the NTSC video signal on the TV monitor70, and a light adjustment circuit 54 for generating a light adjustmentsignal using the output signal of the video process circuit 53, as wellas a sample-and-hold circuit, a low-pass filter, and matrix circuit,which are not shown.

The video process circuit 53 provides a higher S/N ratio of 45 dB for abrightness signal due to an advanced imaging circuit technology. A userwho has used the first endoscope 10 and first video processor 20 canupgrade his/her system performance by installing the second endoscope 40and second video processor 50. Specifically, the image resolution isincreased (from 100000 pixels to 200000 pixels), the observation depthis reduced (from 8 to 100 mm to 3 to 100 mm), and the S/N ratio isincreased (from 40 dB to 45 dB).

Thus, system performance can be upgraded with a minimum cost accordingto the needs from a user. Highest overall performance currentlyavailable can be realized by purchasing the second endoscope 40, secondvideo processor 50, and second light source 60, and using an endoscopeapparatus 4 shown in FIG. 5.

In the endoscope apparatus 4, the second endoscope 40 is connected tothe second light source 60, the second light source 60, to the secondvideo processor 50 via the first connection cable 80 and secondconnection cable 81, and the second video processor 50, to the TVmonitor 70 via the video signal cable 82. Compared with the endoscopeapparatus 1 made up of the first endoscope 10, first video processor 20,and first light source 30, the endoscope apparatus 4 can provideimproved overall performance in terms of observation depth, resolution,quantity of illumination light, light adjustment speed, coloraberration, and S/N ratio.

The second endoscope 40, second video processor 50, and second lightsource 60 may be designed to be more compact and lighter than the firstendoscope 10, first video processor 20, and first light source 30. Notall of the functions of the second endoscope 40, second video processor50, and second light source 60 have higher performance, but some of thefunctions may.

For example, in the second endoscope 40, the sensitivity of the CCD 48may not necessarily be improved to reduce the observation depth of theobservation optical system 46, and the number of fibers forming thelight guide 47 may be reduced to lessen the diameter of the insertiontube 41. In the second video processor 50, the performance of the videoprocess circuit 53 may be upgraded not to increase the S/N ratio but toraise the luminance of images. In the second light source 60, theincreased quantity of light of the illumination lamp 61 may be used toincrease luminance instead of the number of frames.

The first connection cable 80 and second connection cable 81 may beunique to each combination of the models of video processor and lightsource.

In this embodiment, the first video processor 20 and second videoprocessor 50 are of the field sequential type. Therefore, the firstlight source 30 and second light source 60 are also of the fieldsequential type. All of the above-described equipment may instead bebased on simultaneous imaging. The first video processor 20 may be ofthe simultaneous type, and the second video processor 50, of the fieldsequential, or vice versa. In any case, the first and second lightsources 30 and 60 are used in common for simultaneous and fieldsequential imaging.

FIG. 6 shows the second embodiment of the present invention.

The second embodiment is an example of an endoscope system in which alight source can be combined with any one of multiple sets of endoscopesand dedicated video processors.

Specifically, this embodiment can be described as a system configurationwhich is similar to that of the aforesaid endoscope system of the firstembodiment but includes only a first light source 30. Even when thesystem configuration is expanded to include a first endoscope 10, afirst video processor 20, a second endoscope 40, a second videoprocessor 50, etc., a light source (first light source) 30 can be sharedamong the included equipment. The resolution of endoscopic images andthe S/N ratio can be improved without installing a new light source.

The specific configuration and functions shall be represented by theendoscope apparatus 1 of the first embodiment shown in FIG. 2 and theendoscope apparatus 3 shown in FIG. 4.

Herein, both the first video processor 20 and second video processor 50are preferably of either the field sequential or simultaneous type. Thisis because when both video processors are of the same type, the lightsource 30 may be dedicated to field sequential or simultaneous imaging.This reduces the cost and size of the light source 30.

Even when the light source 30 can be used in common for field sequentialand simultaneous imaging, it is preferred that the first and secondvideo processors 20 and 50 are of the same type. This is because thefield sequential and simultaneous imaging modes have unique advantagesand disadvantages. For example, when the field sequential mode isswitched to the simultaneous mode, users may not always be satisfiedwith the resultant images because of unexpected disadvantages ofsimultaneous imaging. On the contrary, when the field sequential mode isexchanged for a technologically-improved field sequential mode, it willnot dissatisfy any user. This is also true for transition from a currentsimultaneous mode to an improved simultaneous mode.

FIGS. 7 to 9 show the third embodiment of the present invention.

According to the third embodiment, an endoscope system having multipleendoscopes, multiple video processors, and multiple light sources,includes at least one endoscope equipped with a CCD compatible with atleast two video processors. As shown in FIG. 7, any one of multiplelight sources can be used in combination with a pair of an endoscope andvideo processor.

Specifically, as shown in FIG. 7, an endoscope system of this embodimentcomprises a first endoscope 90 equipped with a CCD 98, a first videoprocessor 100, a first light source 110, a second endoscope 120 equippedwith a CCD 128, a second video processor 130, and a second light source140. First, as shown in FIG. 8, the first endoscope 90 is connected tothe first light source 110, and the first light source 110, to the firstvideo processor 100 via a first connection cable 80 and a secondconnection cable 81. The first video processor 100 is connected to a TVmonitor 70 via a video signal cable 82. Thus, an endoscope apparatus 5is formed.

The first endoscope 90, similarly to that in the aforesaid firstembodiment, comprises an elongated insertion tube 91 which can beinserted into a subject, a large-diameter operation unit 92 coupled tothe back of the insertion tube 91, and a universal cord 93 extendingfrom the side of the operation unit 92. The first endoscope 90 can befreely disconnected from the first light source 100 by removing aconnector 93a installed at the back of the universal cord 93.

A distal end 94 of the insertion tube 91 is provided with anillumination optical system 95 and an observation optical system 96. Theillumination optical system 95 is facing the emission end of a lightguide 97. A CCD 93 is built in at the image forming position of theobservation optical system 96.

The light guide 97 accommodates the insertion tube 91, operation unit92, and universal cord 93. The incident end of the light guide 97 isarranged at the tip of the connector 93a. A CCD 98 for converting anoptical image of a subject into an electric signal is built in at theimage forming position of the observation optical system 96. Signallines 99a and 99b for transmitting drive and output signals of the CCD98 are routed through the insertion tube 91, operation unit 92, anduniversal cord 93, arranged at the side of the connector 93a, thenconnected to the first video processor 100 via the first connectioncable 80.

The first video processor 100, similarly to that in the aforesaid firstembodiment, is connected to the first endoscope 90 and first lightsource 110 via the first connection cable 80 extending from the side ofthe connector 93a, and to the first light source 110 via the secondconnection cable 81. Similarly to the video processors 20 and 50 in theaforesaid first embodiment, the first video processor 100 comprises aCCD drive circuit 101, a memory 102 for storing the outputs of the CCD93 for three frames associated with R, G, and B field sequential lightcomponents, a video process circuit 103 for reading data of one screen(three frames associated with R, G, and B field sequential lightcomponents) from the memory 102, converting the data into an NTSC videosignal, then displaying the NTSC video signal on the TV monitor 70, anda light adjustment circuit 104 for generating a light adjustment signalfor illumination light according to the output signal of the videoprocess circuit 103.

The first light source 110 has the same configuration as that in theaforesaid first embodiment, comprising an illumination lamp 111, aluminance diaphragm 112, diaphragm drive motor 113, a converging opticalsystem 114 for converging light on the incident end of the light guideof an endoscope connected, and R, G, and B rotary filter 115 installedbetween the converging optical system 114 and luminance diaphragm 112, arotary filter drive motor 116, and a timing signal generation circuit117.

The first video processor 100 is compatible with either first or secondlight source 110 or 140. The first light source 110 or second lightsource 140 feeds a timing signal to each of the CCD drive circuit 101,memory 102, video process circuit 103, and light adjustment circuit 104.The operations of the endoscope apparatus based on the timing signalsare identical to those in the aforesaid first embodiment.

Next, an endoscope apparatus 6 shown in FIG. 9 will be described. Theendoscope apparatus 6 has the same connecting relationships as theendoscope apparatus 5. A second endoscope 120 is connected to a secondlight source 140, and the second light source 140, to a second videoprocessor 130 via a first connection cable 80 and a second connectioncable 81. Then, the second video processor 130 is connected to a TVmonitor 70 via a video signal cable 82.

The second endoscope 120 comprises an elongated insertion tube 121 whichcan be inserted into a subject, a large-diameter operation unit 122coupled to the back of the insertion tube 121, and a universal cord 123extending from the side of the operation unit 122. The second endoscope120 can be freely disconnected from the second light source 140 byremoving a connector 123a installed at the back of the universal cord123.

The universal cord 123 accommodates a light guide 127 whose emission endis facing an illumination optical system 125 installed at a distal end124 of the insertion tube 121, and incident end is arranged at the tipof the connector 123a.

The signal lines 129a and 129b for transmitting drive and output signalsof the CCD 128 which is installed at the image forming position of theobservation optical system 126 located at the distal end 124 passthrough the insertion tube 121, operation unit 122, and universal cord123 to reach the side of the connector 123a.

The second video processor 130, similarly to the first video processor100, comprises a CCD drive circuit 131, a memory 132 for storing theoutputs of the CCD 128 for three frames associated with R, G, and Bfield sequential light components, a video process circuit 133 forreading data of one screen (three frames associated with R, G, and Bfield sequential light components) from the memory 132, converting thedata into an NTSC video signal, then displaying the NTSC video signal onthe TV monitor 70, and a light adjustment circuit 134 for generating alight adjustment signal for illumination light according to the outputsignal of the video process circuit 133. The second video processor 130is connected to the second endoscope 120 and second light source 140 viathe first connection cord 80 extending from the side of the connector123a, and to the second light source 140 via the second connection cable81.

The second video processor 130 is compatible with the first and secondlight sources 110 and 140. The first light source 110 or second lightsource 140 feeds a timing signal to each of the CCD drive circuit 131,memory 132, and video processing circuit 133, thus controlling theoperations of the endoscope apparatus.

The second light source 140 has the same configuration as the firstlight source 110, comprising an illumination lamp 141, a luminancediaphragm 142, a diaphragm drive motor 143, a converging optical system144 for converging light on the incident end of the light guide of anendoscope connected, and R, G, and B rotary filter 145 installed betweenthe converging optical system 144 and luminance diaphragm 142, a rotaryfilter drive motor 146, and a timing signal generation circuit 147.

The second endoscope 120, second video processor 130, and second lightsource 140 forming the endoscope apparatus 6 are improved versions ofthe first endoscope 90, first video processor 100, and first lightsource 110 forming the endoscope apparatus 5.

Specifically, the second endoscope 120 weighs less than the firstendoscope 90 as a whole. Besides, the durability against disinfection orsterilization is improved so that autoclave can be done. The insertiontube 121 of the second endoscope 120 has a smaller external diameter,permitting superb resiliency and flexibility. The light guide 127provides higher permeability, resulting in improved light transmissionefficiency. The CCD 128 has the same chip as the CCD 93 of the firstendoscope 90, which, however, is packaged more compactly.

The CCD drive circuit 131 and memory 132 incorporated in the secondvideo processor 130 ar identical to those in the first video processor100. However, the second video processor 130 is more compact as a whole.The video process circuit 133 and light adjustment circuit 134incorporated in the second video processor 130 have higher performance.

That is to say, in the video process circuit 133, the S/N ratio isincreased, the color reproducibility is improved due to installation ofa color operation matrix circuit, and an electronic zoom function isinstalled. The light adjustment circuit 134 is improved so that it canadjust light properly even when the distal end of an endoscope isoriented in the longitudinal axial direction of an organ or facing thewall of an organ.

The second light source 140 is designed more compactly as a whole thanthe first light source 110, which provides higher luminance because ofthe increased quantity of light of the illumination lamp 141, theupgraded mechanism of the diaphragm drive motor 143, the improved colorbalance of the rotary filter 145, and the larger aperture.

In this case, the CCD 98 in the first endoscope 90 is of the same typeas the CCD 128 in the second endoscope 120, which is compatible with thefirst video processor 100 and second video processor 130. The firstlight source 110 and second light source 140 can be used in combinationwith either the first endoscope 90 or second endoscope 120, and eitherthe first video processor 100 or second video processor 130.

Therefore, users merely have to install necessary equipment according totheir needs and form an endoscope apparatus as shown in FIG. 7. Userswill not incur an enormous load but can implement the results of latesttechnological improvements in equipment whose performance they want toimprove.

Other combinations of the first endoscope 90, first video processor 100,first light source 110, second endoscope 120, second video processor130, and second light source 140 are subject to those for the endoscopeapparatuses 5 and 6. The description will, therefore, be omitted.

The CCD 98 in the first endoscope 90 is not necessarily of the same typeas the CCD 128 in the second endoscope 120. In this case, despite aslightly limited number of combinations of an endoscope and a videoprocessor, the advantages of the present invention deriving from systemexpendability will be exploited satisfactorily.

For example, the CCD 98 in the first endoscope 90 may be compatible bothwith the first and second video processors 100 and 130, while the CCD128 in the second endoscope 120 may be compatible only with the secondvideo processor 130.

In this case, a user who owns first endoscope 90 and first videoprocessor 100 can improve video processing performance merely bypurchasing the second video processor 130. If the user purchases thesecond endoscope 120 in the following fiscal year, he/she will be ableto improve endoscopic performance. Thus, an endoscope system can beupgraded gradually within a limited annual budget.

The CCD 98 in the first endoscope 90 may be compatible only with thefirst video processor 100, while the CCD 128 in the second endoscope 120may be compatible both with the first and second video processors 100and 130. For this endoscope system, for example, the second endoscope120 is purchased in the initial fiscal year, and the second videoprocessor 130, in the following fiscal year. Thus, the endoscope systemcan be upgraded year after year within a limited annual budget.

FIG. 10 shows the fourth embodiment of the present invention.

The fourth embodiment has a system configuration which is similar tothat of the endoscope system of the third embodiment but includes only afirst light source 110. Even when the system configuration is expandedto include a first endoscope 90, a first video processor 100, a secondendoscope 120, a second video processor 130, etc., a light source (firstlight source) 110 can be shared among the included equipment. A newlight source need not be installed. Nevertheless, the endoscopic imageresolution and S/N ratio can be improved.

The specific configuration and functions are identical to those of thethird embodiment, which shall be represented by the endoscope apparatus5 shown in FIG. 8.

FIGS. 11 and 12 show the firth embodiment of the present invention.

The aforesaid embodiments are endoscope systems made up of fieldsequential type equipment, while this embodiment is an endoscope systemmade up of simultaneous type equipment.

This endoscope system includes a first endoscope 150, a first videoprocessor 160, a first light source 170, a second endoscope 180, asecond video processor 190, and a second light source 200, as shown inFIGS. 11 and 12.

In an endoscope apparatus 7 shown in FIG. 11, the first endoscope 150 isconnected to the first light source 170, and the first light source 170,to the first video processor 160 via a first connection cable 80described in the aforesaid first embodiment. The first video processor160 is connected to a TV monitor 70 via a video signal cable 82. Anendoscope apparatus 8 shown in FIG. 12 is formed by connecting thesecond endoscope 180 to the second light source 200, the second lightsource 200 to the second video processor 190 via the first connectioncable 80, and the second video processor 160, to a TV monitor 70 via thevideo signal cable 82.

The first endoscope 150 comprises an elongated insertion tube 151 whichcan be inserted into a subject, a large-diameter operation unit 152coupled to the back of the insertion tube 151, and a universal cord 153extending from the side of the operation unit 152. The first endoscope150 can be freely disconnected from the first light source 170 byremoving a connector 153a installed at the back of the universal cord153.

A rigid distal end 154 is formed at the tip of the insertion tube 151,and provided with an illumination optical system 155 and an observationoptical system 156. The illumination optical system 155 is facing theemission end of a light guide 157. The light guide 157 runs through theinsertion tube 151, operation unit 152, and universal cord 153. Theincident end of the light guide 157 is arranged at the tip of theconnector 153a.

A CCD 158 with a color mosaic filter on its imaging plane is built in atthe image forming position of the observation optical system 156. Signallines 159a and 159b for transmitting drive and output signals of the CCD158 runs through the insertion tube 151, operation unit 152, anduniversal cord 153, and terminates on the side of the connector 153a.

The first video processor 160 comprises a CCD drive circuit 161 fordriving a CCD, a video process circuit 162 for converting the signalsent from the CCD into an NTSC video signal, and displaying the NTSCvideo signal on the TV monitor 70, a light adjustment circuit 163 forgenerating a light adjustment signal using the output signal of thevideo process circuit 162, and a timing signal generation circuit 164for generating a timing signal for determining a CCD drive timing or atiming of reading a signal from the CCD, and feeding the timing signalto each of the CCD drive circuit 161 and video process circuit 162.

The first light source 170 comprises an illumination lamp 171 foremitting white light, a luminance diaphragm 172 for controlling andvarying the quantity of transmission light originating from theillumination lamp 171, a diaphragm drive motor 173 for driving theluminance diaphragm 172, and a converging optical system 174 forconverging light onto the incident end of the light guide of anendoscope connected.

The first video processor 160 and first endoscope 150 are electricallycoupled via the first connection cable 80 extending from the side of theconnector 153a of the universal cord 153. The drive signal sent from theCCD drive circuit 161 passes through the signal line 80b of the firstconnection cable 80, then enters the CCD 158. The output signal sentfrom the CCD 158 passes through the signal line 80a of the firstconnection cable 80, then enters the video process circuit 162.

The first video processor 160 is electrically coupled with the firstlight source 170 via the first connection cable 80. The signal line 80cof the first connection cable 80 is used merely for transmitting thelight adjustment signal sent from the light adjustment circuit 163 tothe diaphragm drive motor 173 of the first light source 170. The firstvideo processor 160 controls the first light source 170.

In this case, the first light source 170 is compatible with either thefirst endoscope 150 or second endoscope 180, and either the first videoprocessor 160 or second video processor 190. The first light source 170supplies properly adjusted light to an endoscope connected over a lightadjustment signal. This is also true for the second light source 200.

On the other hand, in an endoscope apparatus 8 shown in FIG. 12, thesecond endoscope 180 includes an elongated insertion tube 181 which canbe inserted into a subject, a large-diameter operation unit 182 coupledto the back of the insertion tube 181, and a universal cord 183extending from the side of the operation unit 182. The second endoscope180 can be freely disconnected from the second light source 200 byremoving a connector 183a installed at the back of the universal cord183.

The universal cord 183 accommodates a light guide 187 whose emission endis facing an illumination optical system 185 installed at a distal end184 of the insertion tube 181 and incident end is arranged at the tip ofthe connector 183a.

The universal cord 183 accommodates signal lines 189a and 189b fortransmitting drive and output signals of the CCD 188 which is installedat the image forming position of the observation optical system 186located at the distal end 184 and provided with a color mosaic filter onits imaging plane. The signal lines 189a and 189b terminate on the sideof the connector 183a.

The second endoscope 180 is more compact as a whole than the firstendoscope 150, and more durable against disinfection or sterilization sothat it can be autoclaved. The insertion tube 181 has a smaller externaldiameter, providing excellent resiliency and flexibility. The lightguide 187 provides higher permeability, resulting in improvedtransmission efficiency. The CCD 188 employs an on-chip micro lens,providing improved sensitivity. If the CCD 188 chip is identical to theCCD 158 chip, the CCD 188 will also be compatible with the first videoprocessor 160.

A second video processor 190 has the same configuration as the firstvideo processor 160, comprising a CCD drive circuit 191, a video processcircuit 192, a light adjustment circuit 193, and a timing signalgeneration circuit 194. A second light source 200 has the sameconfiguration as the first light source 170, comprising an illuminationlamp 201, a luminance diaphragm 202, a diaphragm drive motor 203, and aconverging optical system 204.

In the second video processor 190, the CCD drive circuit 191 and timingsignal generation circuit 194 are identical to those in the first videoprocessor 160. The second video processor 190 is, however, more compactas a whole. The video process circuit 192 and light adjustment circuit193 provide higher performance.

That is to say, the video process circuit 192 provides a higher S/Nratio, greater color reproducibility due to the modified color operationsystem, and more excellent contrast due to an improved gamma curve. Thelight adjustment circuit 193 is improved so that it can adjust lightproperly even when the distal end of an endoscope is oriented in thelongitudinal axial direction of an organ or facing the wall of an organ.

The second light source 200 is designed more compactly as a whole thanthe first light source 170. The illumination lamp 201 provides a greaterquantity of light, and the diaphragm drive motor 203, higherperformance.

The combinations between the first endoscope 150 or second endoscope180, the first video processor 160 or second video processor 190, andthe first light source 170 or second light source 200 may vary dependingon whether or not the CCD 158 and CCD 188 are of the same type.Specifically, endoscopes, video processors, and light sources arechanged according to the connecting relationships of aforesaidembodiments shown in FIGS. 1, 6 and 10. When the first endoscope 150,first video processor 160, or first light source 170 is upgraded, userscan install only the equipment required to improve system performance.

According to the present invention, it will be apparent that a varietyof embodiments can be formed on a basis of the invention withoutdepartment from the spirit and scope of the invention. This inventionwill be restricted to the appended claims but not limited to anyspecific embodiments.

What is claimed is:
 1. An endoscope system, comprising:a plurality ofdifferent endoscopes each of which has an illumination optical systemfor emitting light outward and an observation optical system for formingan optical image of a subject at a distal end of an insertion tube thatcan be inserted into said subject, and includes a different type ofsolid-state imaging device for converting the optical image of saidsubject formed by said observation optical system into an electricsignal; a plurality of different signal processors each of which iscompatible with one of said plurality of different endoscopes accordingto the type of said solid-state imaging device, for driving saidsolid-state imaging device in simultaneous mode, and for processing theoutput signal of said solid-state imaging device to provide a videosignal; and a light source which is compatible with any one of saidplurality of different endoscopes for supplying light to saidillumination optical system, wherein one of said plurality of differentendoscopes is connected to a compatible one of said plurality ofdifferent signal processors and to said light source, thus forming anendoscope apparatus.
 2. An endoscope system according to claim 1,wherein said endoscope converts the optical image of said subject intoan electrical signal using said solid-state imaging device insimultaneous imaging mode, and said signal processor processes thesignal sent from the solid-state imaging device in said endoscope insimultaneous imaging mode.
 3. An endoscope system, comprising:aplurality of different endoscopes each of which has an illuminationoptical system for emitting light outward and an observation opticalsystem for forming an optical image of a subject at a distal end of aninsertion tube that can be inserted into said subject, and includes adifferent type of solid-state imaging device for converting the opticalimage of said subject formed by said observation optical system into anelectric signal; a plurality of different signal processors each ofwhich is compatible with one of said plurality of different endoscopesaccording to the type of said solid-state imaging device, for drivingsaid solid-state imaging device in field sequential mode, and forprocessing the output signal of said solid-state imaging device toprovide a video signal; and a light source which is compatible with anyone of said plurality of different endoscopes for supplying light tosaid illumination optical system, wherein one of said plurality ofdifferent endoscopes is connected to a compatible one of said pluralityof different signal processors and to said light source, thus forming anendoscope apparatus.
 4. An endoscope system according to claim 1 or 3,wherein the solid-state imaging devices in said plurality of differentendoscopes differ from one another in the number of pixels forming theimaging plane of said solid-state imaging device.
 5. An endoscope systemaccording to claim 1 or 3, wherein the solid-state imaging devices insaid plurality of different endoscopes differ from one another in thedriving mode for said solid-state imaging device.
 6. An endoscope systemaccording to claim 1 or 3, wherein the quantity of light of said lightsource is adjusted according to the signal said signal processorgenerates.
 7. An endoscope system according to claim 1 or 3 wherein saidlight source supplies light to the illumination optical system of saidendoscope, and said signal processor processes the signal sent from thesolid-state imaging device in said endoscope.
 8. An endoscope systemaccording to claim 7 wherein a single timing signal generation circuitfeeds a timing signal for supplying light to said light source, and atiming signal for driving the solid-state imaging device in saidendoscope and processing the output signal sent from said solid-stateimaging device to said signal processor.